Re: [Jaxor-devel] Re: Associating Lists

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Exciting news. I have the core functionality working. I have bumped
into a small conflict where one to many and many to many don't play
nicely together. After I figure out the semantics and fix the
isForeignKey() method that I introduced for the one to many, we will
be in business. I expect to commit this week. It was a good weekend!
Hope yours was as good as mine.

Carl

On Tue, 17 Aug 2004 21:33:33 -0700 (PDT), Michael Rettig
<mik...@ya...> wrote:
> Yes, it can be complicated. I guess I haven't
> implemented anything b/c I haven't run across
> situations where it was difficult to manage manually.
> The code to manually update fields is trivial. Though
> transparency has benefits too. Don't worry about
> changing the DTD. Just change it so the new element or
> attribute is not required and defaults to the current
> implementation. I think adding an element or attribute
> is the only way that this will ever work correctly. It
> cannot always be automatic. There are always
> exceptions. Certainly, we need an attribute to turn
> off automatic relationship management.
> 
> Your example seems sensible, but would make more sense
> to me with some unit tests. Do you have a use case
> from an app you are currently writing? I usually
> create a unit test that satisfies the requirements of
> an app I'm working on in the simplest manner possible.
> Then change the code to meet those requirements.
> 
> Regards,
> 
> Mike
> 
> 
> 
> --- Carl Fyffe <car...@gm...> wrote:
> 
> > I think I see why you have avoided this for so
> > long... it is hard to
> > know exactly what the user is going to want without
> > resorting to the
> > verbose hibernate style dtd. I am trying to avoid
> > changing the DTD at
> > all costs and trying to use the api as it exists to
> > achieve the
> > results we are looking for. The main problem I
> > continue to run into is
> > that of id generation and other things of that
> > nature (filling in
> > details of a linking table that don't neccessarily
> > have anything to do
> > with the links).
> >
> > Forgetting about the linking table details I would
> > like to throw a
> > theory out there.  Please tell me if this holds
> > water.
> >
> >
> >
> > If there are entity ref's to multiple tables, the
> > host table can be
> > thought of as a many to many linking table of some
> > kind.
> >
> > IE groupmembers has two entity ref's, one to groups,
> > one to users.
> > This means jaxor should generate a
> > newInstances(group, userList) and a
> > newInstances(user, groupList) method in the Finder.
> > This is the easy
> > case.
> >
> > Now, lets look at adding a third entity ref.  I
> > couldn't figure out a
> > sensible way to model this with users and groups so
> > I am gonna go with
> > the structure of XML.  Say we wanted to create a
> > generic way to store
> > XML in an RDBMS. We would have tables for documents,
> > elements and
> > attributes. If this was normalized we would only
> > want one instance for
> > each element and attribute. So if we go all the way
> > down to the
> > instance of an attribute we would have something
> > like this:
> >
> > <jaxor
> > package="net.sourceforge.jaxor.example.xml.jaxor">
> >     <entity name="attribute_instance"
> > alias="AttributeInstance" >
> >         <primary-key>
> >             <column name="attribute_instance_id"
> > type="Long"/>
> >         </primary-key>
> >         <column name="element_instance_id"
> > type="Long"/>
> >         <column name="attribute_id" type="Long"/>
> >         <column name="document_id" type="Long"/>
> >
> >         <entity-ref table="element_instance">
> >             <key source="element_instance_id"
> > target="element_instance_id"/>
> >         </entity-ref>
> >         <entity-ref table="attribute">
> >             <key source="attribute_id"
> > target="attribute_id"/>
> >         </entity-ref>
> >         <entity-ref table="document">
> >             <key source="document_id"
> > target="document_id"/>
> >         </entity-ref>
> >
> >     </entity>
> > </jaxor>
> >
> > The attribute instance points to a singular element
> > instance, which in
> > turns points to a concrete element. The attribute
> > instance also points
> > to a concrete attribute and document.
> >
> > In this case, we would want jaxor to generate a
> > bunch of
> > newInstances() methods....  We are only going to
> > want three:
> >
> > newInstances(document, attribute,
> > elementInstanceList)
> > newInstances(document, attributeList,
> > elementInstance)
> > newInstances(documentList, attribute,
> > elementInstance)
> >
> > I don't think it really makes sense to pass in more
> > than one List.
> >
> > Of course it is completely plausible to have a List
> > of groups and a
> > List of users and you want to put all of the users
> > into all of the
> > groups, but does that hold true when you have more
> > than two
> > references?
> >
> > newInstances(documentList, attribute,
> > elementInstance)
> > newInstances(document, attributeList,
> > elementInstance)
> > newInstances(document, attribute,
> > elementInstanceList)
> >
> > newInstances(document, attributeList,
> > elementInstanceList)
> > newInstances(documentList, attribute,
> > elementInstanceList)
> >
> > newInstances(documentList, attributeList,
> > elementInstance)
> >
> > newInstances(documentList, attributeList,
> > elementInstanceList)
> >
> > The matrix only grows if we add another entity ref.
> > Not to mention we
> > still don't have a way to fill in the id's of all of
> > the rows that
> > will be created...
> >
> > Does this make sense, and should I move forward with
> > this strategy?
> >
> 
>                 
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